Bach’s collection of four-part chorale harmonizations is a cornerstone of Western music education, demonstrating masterful voice leading and harmonic practice. Each harmonization is a concise masterpiece of contrapuntal writing and expressive harmony.
Achieving clarity and balance between the four independent voices while maintaining smooth harmonic progressions is the primary challenge.
371 Vierstimmige Choralgesänge is rated Henle level 7 of 9 — late advanced repertoire, roughly ABRSM grade 8 and above. In the RCM system it corresponds to about level 9.
You should be comfortable at Henle level 7 — meaning you can already play level 6–7 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
371 Vierstimmige Choralgesänge is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.